JP4825638B2 - Pixel, organic light emitting display device and driving method thereof - Google Patents

Description

  The present invention relates to a pixel, an organic light emitting display device using the pixel, and a driving method thereof, and in particular, a pixel that can display a uniform luminance image while minimizing the number of transistors included in the pixel. The present invention also relates to an organic light emitting display using this pixel and a driving method thereof.

  Recently, various flat panel display devices capable of reducing the weight and volume, which are disadvantages of a cathode ray tube, have been developed. The flat panel display device includes a liquid crystal display device, a field emission display device, a plasma display panel, and an organic light emitting display device such as an organic light emitting display device.

  Among the flat panel display devices, the organic light emitting display device displays an image using an organic light emitting diode that generates light by recombination of electrons and holes. Such an organic light emitting display device has an advantage of having a quick response speed and being driven with low power consumption.

  FIG. 1 is a circuit diagram illustrating a pixel of a conventional organic light emitting display.

  Referring to FIG. 1, a pixel 4 of a conventional organic light emitting display includes an organic light emitting diode OLED and a pixel circuit 2 connected to the data line Dm and the scanning line Sn for controlling the organic light emitting diode OLED. ing.

  The anode electrode of the organic light emitting diode OLED is connected to the pixel circuit 2 and the cathode electrode is connected to the second power source ELVSS. Such an organic light emitting diode OLED generates light having a predetermined luminance corresponding to the current supplied from the pixel circuit 2.

  When the scanning signal is supplied to the scanning line Sn, the pixel circuit 2 controls the amount of current supplied to the organic light emitting diode OLED corresponding to the data signal supplied to the data line Dm. For this purpose, the pixel circuit 2 is connected between a second transistor M2 connected between the first power supply ELVDD and the organic light emitting diode OLED, and between the second transistor M2, the data line Dm, and the scanning line Sn. The first transistor M1 and the storage capacitor Cst connected between the gate electrode and the first electrode of the second transistor M2 are provided.

  The gate electrode of the first transistor M1 is connected to the scanning line Sn, and the first electrode is connected to the data line Dm. The second electrode of the first transistor M1 is connected to a terminal on one side of the storage capacitor Cst. Here, the first electrode is set to one of the source electrode and the drain electrode, and the second electrode is set to an electrode different from the first electrode. For example, when the first electrode is set as the source electrode, the second electrode is set as the drain electrode. The first transistor M1 connected to the scan line Sn and the data line Dm is turned on when the scan signal is supplied from the scan line Sn, and supplies the data signal supplied from the data line Dm to the storage capacitor Cst. At this time, the storage capacitor Cst is charged with a voltage corresponding to the data signal.

  The gate electrode of the second transistor M2 is connected to one terminal of the storage capacitor Cst, and the first electrode is connected to the other terminal of the storage capacitor Cst and the first power supply ELVDD. The second electrode of the second transistor M2 is connected to the anode electrode of the organic light emitting diode OLED. The second transistor M2 controls the amount of current flowing from the first power supply ELVDD to the second power supply ELVSS via the organic light emitting diode OLED corresponding to the voltage value stored in the storage capacitor Cst. At this time, the organic light emitting diode OLED generates light corresponding to the amount of current supplied from the second transistor M2.

  However, there is a problem that the pixels 4 of the conventional organic light emitting display device cannot display an image with uniform brightness. More specifically, the threshold voltage of the second transistor M2 included in each pixel 4 is set to be different for each pixel 4 due to process variations and the like. As described above, when the threshold voltages of the second transistors M2 are set to be different, even if data signals indicating the same gradation are supplied to a large number of pixels 4, the difference between the threshold voltages of the second transistors M2 causes each other. Light of different brightness is generated by the organic light emitting diode OLED.

  On the other hand, in order to overcome such a problem, a method has been proposed in which a number of transistors are additionally formed in the pixel circuit 2 to compensate the threshold voltage of the second transistor M2. Actually, a method of compensating for the threshold voltage of the second transistor M2 by adding six or more transistors to the pixel circuit 2 is used. However, if the pixel circuit 2 includes six or more transistors, the structure of the pixel circuit 2 becomes complicated, and an additional wiring for controlling the transistors included in the pixel circuit 2 is required. Further, even if the pixel circuit 2 includes a large number of transistors, there is a problem that characteristics such as mobility of the second transistor M2 cannot be compensated.

Japanese Unexamined Patent Publication No. 2002-72926 Japanese Unexamined Patent Publication No. 6-270462 Korean Patent Publication No. 10-1998-060018

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pixel capable of minimizing the number of transistors included in the pixel and displaying a uniform luminance image, an organic light emitting display using the pixel, and a driving method thereof. Is to provide.

  To achieve the above object, a pixel according to an embodiment of the present invention includes a first transistor having a gate electrode connected to a scan line and a first electrode connected to a data line, and a second electrode of the first transistor. A second electrode having a gate electrode connected thereto, a first electrode connected to a first power source, a gate electrode connected to the scanning line, a first electrode connected to the first power source, and a second electrode connected to the first power source A third transistor connected to the second electrode of the second transistor; an organic light emitting diode having an anode electrode connected to the second electrode of the second transistor and the third transistor and a cathode electrode connected to a second power source; A storage capacitor connected between the gate electrode and the first electrode of the second transistor, and a feed connected between the gate electrode and the second electrode of the second transistor. Characterized in that it comprises a Kkukyapashita.

  An organic light emitting display according to an embodiment of the present invention sequentially supplies a scan signal to a scan line, a scan driver for sequentially supplying a light emission control signal to a light emission control line, and a data signal to a data line. And a plurality of pixels connected to the scan line and the data line, each of the pixels being connected to the scan line and the data line and being supplied with the scan signal A first transistor that is turned on; a storage capacitor that is positioned between a second electrode of the first transistor and a first power supply and that charges a voltage corresponding to the data signal when the first transistor is turned on; A second transistor that controls the amount of current flowing from the first power source to the second power source through the organic light emitting diode in response to the voltage charged in the storage capacitor. A third transistor for supplying a voltage of the first power source to a second electrode of the second transistor when a scanning signal is supplied to the scanning line; and a gate electrode and a second electrode of the second transistor. And a feedback capacitor that transmits a voltage change amount of the second electrode of the second transistor to the gate electrode of the second transistor when a current is supplied to the organic light emitting diode. To do.

  The driving method of the organic light emitting display device according to the embodiment of the present invention includes a step of supplying a scanning signal to a scanning line and charging a voltage corresponding to the data signal to the storage capacitor; When the voltage is charged, the step of holding the second electrode of the driving transistor at the voltage of the first power source and the current corresponding to the voltage charged in the storage capacitor are organically generated from the first power source by the driving transistor. A voltage supply amount corresponding to a difference between a voltage applied to the organic light emitting diode and the first power source when a current is supplied to the organic light emitting diode; Controlling the voltage of the gate electrode of the driving transistor based on the driving voltage, and controlling the voltage of the gate electrode of the driving transistor. Characterized in that it comprises a step of supplying a current to the organic light emitting diode.

  As described above, according to the pixel according to the embodiment of the present invention, the organic light emitting display device using the pixel, and the driving method thereof, the voltage change amount of the second electrode of the driving transistor is determined using the feedback capacitor. Since negative feedback is provided to the gate electrode of the driving transistor, variations in the threshold voltage of the driving transistor can be compensated to some extent. Further, since the voltage fed back to the gate electrode of the drive transistor is determined by the amount of current flowing from the drive transistor, the mobility characteristic of the drive transistor can be compensated to some extent. At the same time, the present invention has an advantage that the threshold voltage of the driving transistor can be compensated by using only four transistors and two capacitors. Further, since each pixel is connected to one scanning line, there is an advantage that no additional wiring is required.

  Hereinafter, preferred embodiments in which a person having ordinary knowledge in the technical field of the present invention can easily implement the present invention will be described in detail with reference to FIGS. 2 to 7c.

  FIG. 2 is a diagram illustrating a configuration of an organic light emitting display according to an embodiment of the present invention.

  Referring to FIG. 2, the organic light emitting display according to an embodiment of the present invention includes a plurality of pixels 140 positioned to be connected to scan lines S1 to Sn, light emission control lines E1 to En, and data lines D1 to Dm. A pixel driver 130, a scan driver 110 for driving the scan lines S1 to Sn and the light emission control lines E1 to En, a data driver 120 for driving the data lines D1 to Dm, and a scan driver 110. And a timing control unit 150 for controlling the data driving unit 120.

  The scan driver 110 is supplied with a scan drive control signal SCS from the timing controller 150. The scan driver 110 supplied with the scan drive control signal SCS generates a scan signal and sequentially supplies the generated scan signal to the scan lines S1 to Sn. The scan driver 110 generates a light emission control signal in response to the scan drive control signal SCS, and sequentially supplies the generated light emission control signal to the light emission control lines E1 to En. Here, the cycle of the light emission control signal is set to be the same as or wider than the scanning signal. Actually, the cycle of the light emission control signal supplied to the i (i is a natural number) light emission control line is set so as to be superimposed on the scanning signal supplied to the i th scanning line.

  The data driver 120 is supplied with a data drive control signal DCS from the timing controller 150. The data driver 120 supplied with the data driving control signal DCS generates a data signal and supplies the generated data signal to the data lines D1 to Dm so as to be synchronized with the scanning signal.

  The timing controller 150 generates a data drive control signal DCS and a scan drive control signal SCS in response to a synchronization signal supplied from the outside. The data drive control signal DCS generated by the timing controller 150 is supplied to the data driver 120, and the scan drive control signal SCS is supplied to the scan driver 110. The timing controller 150 supplies data Data supplied from the outside to the data driver 120.

  The pixel unit 130 is supplied with the first power ELVDD and the second power ELVSS from the outside and supplies them to the respective pixels 140. Each of the pixels 140 supplied with the first power ELVDD and the second power ELVSS generates light corresponding to the data signal. Here, the light emission time of the pixel 140 is controlled by a light emission control signal. On the other hand, the first power supply ELVDD is set to a voltage value higher than that of the second power supply ELVSS.

  FIG. 3 is a circuit diagram illustrating a pixel according to an embodiment of the present invention. FIG. 3 shows pixels connected to the nth scanning line Sn and the mth data line Dm for convenience of explanation.

  Referring to FIG. 3, a pixel 140 according to an embodiment of the present invention includes an organic light emitting diode OLED, a pixel circuit 142 connected to the data line Dm, the scanning line Sn, and the light emission control line En and controlling the organic light emitting diode OLED. It has.

  The anode electrode of the organic light emitting diode OLED is connected to the pixel circuit 142, and the cathode electrode is connected to the second power source ELVSS. Such an organic light emitting diode OLED generates light having a predetermined luminance corresponding to the current supplied from the pixel circuit 142.

  When the scanning signal is supplied to the scanning line Sn, the pixel circuit 142 controls the amount of current supplied to the organic light emitting diode OLED corresponding to the data signal supplied to the data line Dm. On the other hand, when a predetermined current is supplied from the driving transistor included in the pixel circuit 142 to the organic light emitting diode OLED, a predetermined voltage is applied to the organic light emitting diode OLED. In this case, the pixel circuit 142 inputs a predetermined voltage applied to the organic light emitting diode OLED to the gate electrode of the driving transistor as a negative feedback to compensate for the threshold voltage and mobility of the driving transistor. Yes.

  For this purpose, the pixel circuit 142 includes first to fourth transistors M1 to M4, a storage capacitor Cst, and a feedback capacitor Cfb.

  The gate electrode of the first transistor M1 is connected to the scanning line Sn, and the first electrode is connected to the data line Dm. The second electrode of the first transistor M1 is connected to the gate electrode of the second transistor M2 (drive transistor). When the scan signal is supplied to the scan line Sn, the first transistor M1 supplies the data signal supplied to the data line Dm to the gate electrode of the second transistor M2.

  The gate electrode of the second transistor M2 is connected to the second electrode of the first transistor M1, and the first electrode is connected to the first power supply ELVDD. The second electrode of the second transistor M2 is connected to the first electrode of the fourth transistor M4. The second transistor M2 controls the amount of current flowing from the first power supply ELVDD to the second power supply ELVSS via the organic light emitting diode OLED corresponding to the voltage applied to its gate electrode.

  The gate electrode of the third transistor M3 is connected to the scanning line Sn, and the first electrode is connected to the first power supply ELVDD. The second electrode of the third transistor M3 is connected to the first electrode of the fourth transistor M4. The third transistor M3 supplies the voltage of the first power supply ELVDD to the first electrode of the fourth transistor M4 when the scanning signal is supplied.

  The first electrode of the fourth transistor M4 is connected to the second electrodes of the second transistor M2 and the third transistor M3, and the second electrode is connected to the organic light emitting diode OLED. The gate electrode of the fourth transistor M4 is connected to the light emission control line En. The fourth transistor M4 is turned off when the light emission control signal is supplied to the light emission control line En, and is turned on in other cases. Such a fourth transistor M4 can also be removed. In this case, the second electrode of the second transistor M2 is directly connected to the anode electrode of the organic light emitting diode OLED.

  One terminal of the storage capacitor Cst is connected to the gate electrode of the second transistor M2, and the other terminal is connected to the first power supply ELVDD. The storage capacitor Cst is charged with a voltage corresponding to the data signal when the first transistor M1 is turned on.

  One terminal of the feedback capacitor Cfb is connected to the gate electrode of the second transistor M2, and the other terminal is connected to the second electrode of the second transistor M2. Such a feedback capacitor Cfb feeds back the voltage change amount of the second electrode of the second transistor M2 to the gate electrode of the second transistor M2.

  Next, a driving method of the organic light emitting display according to the present invention will be described with reference to the drawings. FIG. 4 is a diagram illustrating waveforms of signals supplied to the pixels shown in FIG.

  Referring to FIG. 4, first, before the scanning signal is supplied to the scanning line Sn, the emission control signal is supplied to the emission control line En, the fourth transistor M4 is turned off, and the second transistor M2 and the organic light emitting diode OLED are connected. Electrically shut off. Thereafter, a scanning signal is supplied to the scanning line Sn, and the first transistor M1 and the third transistor M3 are turned on.

  When the first transistor M1 is turned on, the data voltage Vdata corresponding to the data signal is applied to the first node N1, as shown in FIG. Then, the storage capacitor Cst is charged with a voltage corresponding to the difference between the data voltage Vdata and the first power supply ELVDD. When the third transistor M3 is turned on, the voltage of the first power supply ELVDD is supplied to the second node N2, and the second electrode of the second transistor M2 is held at the voltage of the first power supply ELVDD.

  Thereafter, as shown in FIG. 4, the supply of the scanning signal supplied to the scanning line Sn and the emission control signal supplied to the emission control line En are interrupted. Then, as shown in FIG. 6, the first transistor M1 and the third transistor M3 are turned off, and the fourth transistor M4 is turned on.

  At this time, the second transistor M2 supplies a current corresponding to the voltage applied to the first node N1, that is, the voltage charged in the storage capacitor Cst, to the organic light emitting diode OLED. In this case, the voltage of the second node N2 changes as in relational expression 1.

(Relational formula 1)
ΔN2 = ELVDD−V _OLED

In the relational expression 1, V _OLED represents a voltage applied to the organic light emitting diode OLED corresponding to a current flowing through the organic light emitting diode OLED. Accordingly, the voltage V _OLED increases in proportion to the amount of current flowing.

  Referring to the relational expression 1, the voltage of the second node N2 falls from the voltage of the first power supply ELVDD by the voltage applied to the organic light emitting diode OLED. Then, the voltage of the first node N1 set in the floating state by the feedback capacitor Cfb changes. Actually, the amount of voltage change at the first node N1 is set as in relational expression 2.

(Relational expression 2)
ΔN1 = Vdata−Cfb / (Cst + Cfb) × ΔN2

  That is, the voltage of the first node N1, which is the voltage of the gate electrode of the second transistor M2, changes corresponding to the voltage change amount of the second node N2. Here, since the voltage change amount of the second node N2 changes in relation to the threshold voltage of the second transistor M2, the voltage change amount of the first node N1 changes corresponding to the threshold voltage of the second transistor M2. .

  Thereafter, the second transistor M2 supplies a current corresponding to the voltage applied to the first node N1 to the organic light emitting diode OLED, and the organic light emitting diode OLED has a predetermined luminance corresponding to the current supplied thereto. Produce light.

  As described above, in the present invention, the voltage applied to the organic light emitting diode OLED corresponding to the amount of current supplied from the second transistor M2 to the organic light emitting diode OLED is determined using the feedback capacitor Cfb. Transmit to the gate electrode. Here, since the current supplied from the second transistor M2 to the organic light emitting diode OLED is affected by the threshold voltage of the second transistor M2, variations in the threshold voltage of the second transistor M2 can be compensated to some extent. This will be described in detail with reference to Table 1.

  Table 1 compares the case where the threshold voltage of the second transistor M2 is small (small) and large (large) when the same data signal is supplied.

Referring to Table 1, first, when the threshold voltage Vth of the second transistor M2 is small, a large amount of current corresponding to the data signal is supplied to the organic light emitting diode OLED (I _OLED = large). In this case, a high voltage corresponding to the current supplied to the organic light emitting diode OLED is applied (V _OLED = large).

Here, the second node N2, to change the voltage _{V OLED} is applied to the OLED from the first power source ELVDD, and a voltage change amount is set small (ΔN2 = small). Similarly, the voltage change amount of the first node N1 that changes corresponding to the voltage change amount of the second node N2 is also set small (ΔN1 = small). Thus, when the voltage change amount of the first node N1 is set small, the amount of current flowing through the organic light emitting diode OLED also changes within a small range (ΔI _OLED = small). Therefore, the current finally flowing through the organic light emitting diode OLED changes by a small amount with respect to the current _IOLED corresponding to the data signal.

On the other hand, when the threshold voltage Vth of the second transistor M2 is high, a small amount of current corresponding to the data signal is supplied to the organic light emitting diode OLED (I _OLED = small). In this case, a low voltage corresponding to the current supplied to the organic light emitting diode OLED is applied (V _OLED = small).

Here, the second node N2, to vary in response to the voltage _{V OLED} applied to the organic light emitting diode OLED from the first power supply ELVDD, and a voltage change amount is set larger (ΔN2 = large). Similarly, the voltage change amount of the first node N1 that changes corresponding to the voltage change amount of the second node N2 is also set large (ΔN1 = large). Thus, when the amount of voltage change at the first node N1 is set large, the amount of current flowing through the organic light emitting diode OLED also changes within a high range (ΔI _OLED = large). Therefore, the current that finally flows through the organic light emitting diode OLED varies in a large amount with respect to the current _IOLED corresponding to the data signal.

  In other words, according to the present invention, the amount of current flowing through the organic light emitting diode OLED changes corresponding to the threshold voltage of the second transistor M2, and thus an image with uniform brightness can be displayed. Further, the present invention has an advantage that the pixel 140 can be realized with a relatively simple circuit using four transistors and two capacitors.

  On the other hand, since the voltage corresponding to the amount of current flowing through the organic light emitting diode OLED is fed back, it is possible to predict the case where the pixel 140 includes a predetermined resistance. However, it is practically impossible to form a resistor having the same capacitance in each pixel 140 in the current process. In other words, the resistance variation among the resistors formed in each of the pixels 140 is significant, and it is difficult to achieve a desired purpose. In order to overcome such a problem, in the present invention, a voltage applied to the organic light emitting diode OLED is fed back to the gate electrode of the second transistor M2 using the feedback capacitor Cfb.

  FIGS. 7A to 7C are graphs showing changes in the current flowing through the pixel according to the embodiment of the present invention and the conventional pixel corresponding to the change in the threshold voltage.

  Referring to FIGS. 7a to 7c, when a current of 10 nA is first supplied to the organic light emitting diode OLED as shown in FIG. 7a, the driving transistor (ie, the second transistor M2) in the conventional pixel shown in FIG. A large amount of current (changes to about 80% of 10 nA) changes corresponding to the change in threshold voltage. However, in the pixel according to the embodiment of the present invention shown in FIG. 3, only a small amount of current (change to 35% of about 10 nA) changes corresponding to the switching of the threshold voltage of the drive transistor M2.

  Also, as shown in FIG. 7b, when a current of 100 nA is supplied to the organic light emitting diode OLED, in the conventional pixel, the current changes to about 35% of 100 nA corresponding to the change of the threshold voltage of the driving transistor M2. On the other hand, in the pixel of the present invention, the current changes only to about 15% of 100 nA corresponding to the change of the threshold voltage of the driving transistor M2. Similarly, when a current of 200 nA is supplied to the organic light emitting diode OLED as shown in FIG. 7c, in the conventional pixel, the current changes to about 25% of 200 nA corresponding to the change of the threshold voltage of the driving transistor M2. On the other hand, in the pixel of the present invention, the current changes only to about 12% of 200 nA corresponding to the change of the threshold voltage of the driving transistor M2. That is, in the pixel according to the embodiment of the present invention, variations in the threshold voltage of the drive transistor M2 can be compensated to some extent.

  The foregoing detailed description of the invention and the drawings are merely exemplary of the invention, which is used for the purpose of illustrating the invention and is described in the meaning limitations and the claims. It has not been used to limit the scope of the invention described. Therefore, it will be understood from the above contents that various changes and modifications can be made by those skilled in the art without departing from the technical idea of the present invention. Therefore, the technical protection scope of the present invention is not limited to the contents described in the detailed description of the specification, but must be defined by the claims.

It is a circuit diagram which shows the structure of the conventional pixel. 1 is a diagram illustrating a configuration of an organic light emitting display device according to an embodiment of the present invention. It is a circuit diagram which shows the structure of the pixel which concerns on the Example of this invention. It is a figure which shows the waveform of the signal supplied to the pixel shown in FIG. FIG. 5 is a diagram illustrating an operation process of a pixel driven by the drive signal of FIG. 4. FIG. 5 is a diagram illustrating an operation process of a pixel driven by the drive signal of FIG. 4. 6 is a graph showing a change in current flowing in a pixel according to an embodiment of the present invention and a current flowing in a conventional pixel in response to a change in threshold voltage. 6 is a graph showing a change in current flowing in a pixel according to an embodiment of the present invention and a current flowing in a conventional pixel in response to a change in threshold voltage. 6 is a graph showing a change in current flowing in a pixel according to an embodiment of the present invention and a current flowing in a conventional pixel in response to a change in threshold voltage.

Explanation of symbols

2, 142 pixel circuit 4, 140 pixel 110 scan driving unit 120 data driving unit 130 pixel unit 150 timing control unit

Claims (8)

A first transistor having a gate electrode connected to the scan line and a first electrode connected to the data line;
A second transistor having a gate electrode connected to a second electrode of the first transistor and a first electrode connected to a first power source;
A third transistor having a gate electrode connected to the scan line, a first electrode connected to the first power source, and a second electrode connected to a second electrode of the second transistor;
An organic light emitting diode having an anode electrode connected to a second electrode of the second transistor and the third transistor and a cathode electrode connected to a second power source;
A storage capacitor connected between the gate electrode and the first electrode of the second transistor;
A feedback capacitor connected between the gate electrode and the second electrode of the second transistor;
The first electrode of the second transistor is a source electrode;
A scan signal is supplied to the scan line to charge the storage capacitor with a voltage corresponding to the data signal, and a current corresponding to the voltage charged to the storage capacitor is supplied from the first power source by the second transistor. When supplying the second power source via the organic light emitting diode,
While feeding back the voltage change amount corresponding to the difference between the voltage applied to the organic light emitting diode and the voltage of the first power source to the gate electrode of the second transistor via the feedback capacitor, the voltage of the gate electrode And a current is supplied from the second transistor to the organic light emitting diode.   It is connected between the anode electrode of the organic light emitting diode and the second electrode of the second transistor, and is turned off when the voltage corresponding to the data signal is charged in the storage capacitor, and turned on otherwise. The pixel according to claim 1, further comprising a fourth transistor.   The pixel according to claim 1, wherein the first power source is set to a voltage value higher than that of the second power source. A scan driver for sequentially supplying scanning signals to the scanning lines and sequentially supplying light emission control signals to the light emission control lines;
A data driver for supplying a data signal to the data line;
A plurality of pixels connected to the scanning line , the light emission control line and the data line,
Each of the pixels
A first transistor connected to the scan line and the data line and turned on when the scan signal is supplied;
A storage capacitor located between the second electrode of the first transistor and a first power source, and charging a voltage corresponding to the data signal when the first transistor is turned on;
A second transistor that controls an amount of current flowing from the first power source to the second power source through the organic light emitting diode in response to a voltage charged in the storage capacitor;
A third transistor for supplying a voltage of the first power source to a second electrode of the second transistor when a scanning signal is supplied to the scanning line;
The voltage change amount of the second electrode of the second transistor is between the gate electrode of the second transistor and the second electrode of the second transistor when a current is supplied to the organic light emitting diode. A feedback capacitor for transmitting to,
A fourth transistor located between the second electrode of the second transistor and the organic light emitting diode, turned off when the light emission control signal is supplied, and turned on otherwise .
The second electrode of the second transistor is a drain electrode;
The organic light emitting diode has an anode electrode connected to the second electrode of the second transistor and the third transistor, and a cathode electrode connected to the second power source,
The organic light emitting display device, wherein the scan driver supplies a light emission control signal to the pixel via the light emission control line before supplying the scan signal to the pixel via the scan line . i (i is a natural number) according to claim 4, characterized in that there is a period of overlap with a scanning signal supplied to the emission control signal and, i-th scanning line to be supplied to the second emission control line Organic electroluminescent display device. Supplying a scanning signal to the scanning line and charging the storage capacitor with a voltage corresponding to the data signal;
When voltage corresponding to the data signal to the storage capacitor Ru is charged, a step for holding the second electrode of the driving transistor to the voltage of the first power source,
Supplying a current corresponding to a voltage charged in the storage capacitor from the first power source to the second power source via the organic light emitting diode by the driving transistor;
When a current is supplied to the organic light emitting diode, a voltage change amount corresponding to a difference between the voltage applied to the organic light emitting diode and the first power source is fed back to the gate electrode of the driving transistor through a feedback capacitor. Controlling the voltage of the gate electrode;
Supplying a current to the organic light emitting diode from a driving transistor in which a voltage of the gate electrode is controlled,
The second electrode of the driving transistor is Ri drain electrode der,
The feedback capacitor the method for driving the organic light emitting display device, characterized in that that will be connected between the gate electrode and the drain electrode of the driving transistor. Using a feedback capacitor which is provided between the gate electrode and the second electrode of the driving transistor, according to claim 6, wherein controlling the voltage of the gate electrode of the driving transistor based on the voltage variation Driving method of organic electroluminescence display device. When charging voltage to the storage capacitor, according to any one of claims 6 or claim 7, characterized in that it comprises further the step of electrically disconnecting the said driving transistor and the organic light emitting diode A driving method of an organic light emitting display device.

Images